Speaking in front of lawmakers at South Korea’s national assembly, the US president offered a "brighter path" if Pyongyang abandoned its weapons program, leaving the door open to diplomacy, but also warned that the US was prepared to use military means if necessary.

The regime has interpreted America's past restraint as weakness. This would be a fatal miscalculation, Trump said adding that North Korea's Kim Jong-un continues to launch missiles over the sovereign territory of Japan and all other neighbors, test nuclear devices, and develop ICBMs to threaten the United States itself.

"The weapons you are acquiring are not making you safer, they are putting your regime in grave danger," Trump said, adding : "Every step you take down this dark path increases the peril you face." "We will offer a path to a much better future," he said. "It begins with an end to the aggression of your regime, a stop to your development of ballistic missiles, and complete, verifiable and total denuclearization."

The address has also drew heavily upon the long history of American military support for South Korea, with references to the Korean War-era Inchon landings and the Battle of Pork Chop Hill that featured tens of thousands of American servicemen flooding the peninsula to counter the advance of communism on the peninsula.

Trump used the economic successes of South Korea in the decades since that war to further deride the hermit nation to the north.

"North Korea is a country ruled by a cult. At the centre of this military cult is a deranged belief in the ruler's destiny to rule as a parent protector over a conquered Korean Peninsula," Trump said.

"The more successful South Korea becomes the more successfully you discredit the dark fantasy at the heart of the North Korean regime."

Meanwhile, a large banner read during a protest near the United States Embassy in Seoul on Tuesday, saying "No Trump, no war!", "Don’t come, Trump! You talk about war whenever you open your mouth.

"Hundreds of labour activists and other progressives shouted in downtown Seoul, "Go away, Trump!" where thousands of police officers were deployed to keep security.